Populations of the light blue-gray animal, which lives in China's polluted Yangtze River, have plummeted over the last 30 years.

A possible sighting in August 2007 is currently being investigated by Chinese scientists, but even if one or two dolphins are found, the baiji is almost certainly doomed.

Freshwater dolphins are very vulnerable, because rivers tend to be heavily used by humans and there is nowhere else for the dolphins to go, Caroline Pollock, a Red List program officer, told National Geographic News.